Just a standard main jet. Was glad that Dennis Kirk had a good selection of these even if they were hard to find on their web site. I actually followed a google search link to them. I could not find them by searching their site. They work as well as any.

BEST ANSWER:Usually yz250 two strokes have mikuni carbs, then it would be no. I believe some years did run a keihin, then yes they would fit. Check your carb. The manufacturer name should be cast in carb body, usually large

BEST ANSWER:Usually yz250 two strokes have mikuni carbs, then it would be no. I believe some years did run a keihin, then yes they would fit. Check your carb. The manufacturer name should be cast in carb body, usually large